it's only fitting that TV's most famous chemistry teacher would narrate a show about salt, seen here in its molecular form. / H2

by Gary Levin, USA TODAY

by Gary Levin, USA TODAY

Bryan Cranston has played TV's most beloved (or reviled) chemistry teacher. Now he's turning history prof.

Cranston is the narrator of Big History, a new series on History's smaller, more historical cable sibling, H2, premiering Saturday (10 p.m. ET/7 p.m. PT).

The 10-hour series, based on a curriculum developed in 1989 by David Christian (and backed by Bill Gates), takes an expansive view of seemingly pedestrian topics, using astronomy, physics and chemistry to explain history across time and geography.

"I don't want it to seem like a lecture," says Cranston, who found the series "intriguing and insightful. It's fascinating that things we use in everyday life, that we take for granted, have such origins. We break it down and show how it affects your life."

The opening half-hour episodes (two air each week) explain the role salt and horses played in shaping history.

Salt, a well-known preservative, allowed Egyptians to mummify; a tax on it funded the building of the Great Wall of China; and sodium is the key ingredient in thought because it transmits signals between brain cells.

Horses led the ancient Romans to wear pants instead of tunics; helped spread languages across the world; and as a "primary vehicle of conquest" were a key to building empires. Their importance persists in the continued use of the automotive term "horsepower."

Other episodes focus on gold, meteors, cellphones, mountains, caffeine and ice. And a two-hour finale, airing Dec. 28, assembles the puzzle pieces chronologically in unexpected ways, explaining the universe from the Big Bang to the present.

"It's hard to make smart stuff fun," says Paul Cabana, programming chief of the 2-year-old network, which reaches 70 million homes. "To try to touch on 13.8 billion years of history was so incredibly ambitious, we thought we'd go for it."

Cranston is going for new territory after concluding his acclaimed role on AMC's Breaking Bad, and he says he's pleased at audience reaction to the finale, which achieved the "trick" of preserving the show's tone without having to "compromise a little bit so everyone could feel happy with the outcome." (As for theories the finale's ending was a dream concocted by series creator Vince Gilligan, Cranston chuckles, "I don't think he intended to do that.")

He's headed to Broadway, probably in March, with All the Way, in which he stars as "bombastic, dynamic" President Lyndon B. Johnson after a successful run in Boston, which he called "absolutely exhausting; it would kick my (butt) every night, but in a good way."

Later next year he'll star as blacklisted screenwriter Dalton Trumbo in a film directed by Jay Roach. And this week he's directing the Christmas episode of ABC's hit Modern Family.

He says Big History's goal is to entertain while it teaches, requiring some "artistic license." And the concept in general has doubters among some historians, who argue broad generalizations across thousands of years are used to make sometimes arbitrary connections.

Segments from the series will be used in a free online course designed for high school curriculums at bighistoryproject.com.

Which is fitting, because "when I watch a show, I want to learn something," Cranston says.

So what did he learn from Breaking Bad?

"That every single person alive, as meek and mild as they seem, can be dangerous given the right set of circumstances."